JP2003347231A - Method of manufacturing compound semiconductor and semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a III-V compound semiconductor having a large nitrogen atom composition can be manufactured easily, and to provide a semiconductor element manufactured by the method. <P>SOLUTION: In the method, the III-V compound semiconductor containing at least both arsenic atoms and nitrogen atoms as group V atoms is manufactured by the vapor phase growth method by using a gaseous starting material of nitrogen. In this method, the ratio of the partial pressure of a gaseous starting material of arsenic to the sum of partial pressures of group III gaseous starting materials in a reaction chamber is controlled to ≤1. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a III-V compound semiconductor containing at least both arsenic atoms and nitrogen atoms as group V atoms, and a semiconductor device.
The present invention relates to a compound semiconductor manufacturing method and a semiconductor element in which the composition of nitrogen atoms is increased by devising a partial pressure ratio of an arsenic source gas.

[0002]

2. Description of the Related Art As a laser for optical communication, a 1.3 μm band is used.
Alternatively, the 1.55 μm band is used. Especially 1.3
The μm band laser is used for short-distance optical communication, but at present, InGa which is a group III-V compound semiconductor is used.
AsP / InP-based materials are mainly used. However, this material system requires the use of an InP substrate, which increases the substrate cost. In addition, the conduction band discontinuity (band offset amount) at the hetero barrier in the active layer is small, and electrons are not activated. Since it is easy to leak out of the layer, deterioration of characteristics during high-temperature operation is a problem. Normally, a method such as cooling with a Peltier element is used to stably operate even at high temperatures, but this causes a problem that device cost is increased and power consumption is increased.

On the other hand, Jpn. J. Appl. Phys.
Vol. 35 (1996) Pt. 1, No. 11, p.
5711 has II other than InGaAsP / InP-based materials.
As a group IV compound semiconductor, GaInNAs obtained by adding nitrogen to GaInAs has been proposed as a material that can be epitaxially grown on GaAs and covers a wavelength region of 1.3 μm to 1.55 μm.

When In is added to GaAs, the lattice constant of GaInAs becomes larger than that of GaAs because In has a larger atomic radius than that of Ga. The same lattice constant can be used.

Further, GaInNAs is made of GaInAs.
Unlike many III-V compound semiconductors such as P, G
Even if N having a smaller atomic radius than As is added to aAs, the band gap wavelength can be shortened. Therefore, by appropriately designing the composition of In and N, the GaAs
A group III-V compound semiconductor having a band gap wavelength of 1.3 μm or 1.55 μm lattice-matched to the above is obtained.

As a crystal growth method of GaInNAs, there are a molecular beam epitaxy (MBE) method, a metal organic vapor phase epitaxy (MOVPE) method, and the like. To manufacture a low-cost device, a large number of substrates are simultaneously crystallized. An MOVPE method that can grow is advantageous. In the MOVPE method, a gas such as hydrogen or nitrogen is passed through an organometallic compound maintained at a constant temperature, and the raw material is supplied in a gaseous state together with a large amount of a carrier gas composed of hydrogen or nitrogen into a reaction vessel.
The crystal is grown by thermal decomposition. Usually, the growth is performed by increasing the partial pressure of the group V source gas by several to several thousand times as compared with the partial pressure of the group III source gas.

[0007] Since GaInNAs is a highly immiscible material, it is difficult to increase the composition of nitrogen atoms.

[0008] Therefore, as a conventional method for producing a compound semiconductor, in order to increase the composition of nitrogen atoms, a non-equilibrium is grown at a low temperature to grow, and 1,1-dimethylhydrazine which is easily decomposed even at a low temperature. Using an organic nitrogen compound (S. Sato et. Al. Jpn.
Appl. Phys. Vol. 36 (1997) Pt.
1, No. 5A, p. 2671) or a method using a nitrogen carrier gas (A. Ougazzaden et.a.
l. Jpn. J. Appl. Phys. Vol. 38
(1999) Pt. 1, No. 2B, p. 1019).

[0009]

However, in the conventional method of manufacturing a compound semiconductor, GaIn has good crystallinity.
To obtain NAs, the composition of the nitrogen atom is 1-2.
% Is the limit and there is a problem that the composition of nitrogen atoms is small.

This is because the reactive species of arsenic easily adhere to the crystal surface, the reactive species of nitrogen hardly adhere to the crystal surface, the arsenic atoms once adhered to the crystal surface are less likely to be eliminated again, and This is due to the difference in the properties of the arsenic atom and the nitrogen atom that atoms are easily detached.

For this reason, GaI having a large composition of nitrogen atoms is used.
In order to obtain an nNAs crystal, a crystal growth method for controlling the attachment and detachment of arsenic reactive species and nitrogen reactive species on the crystal surface is required.

In a semiconductor element (semiconductor light emitting device) using GaInNAs manufactured by a conventional manufacturing method, the composition of nitrogen atoms cannot be increased in order to obtain an emission wavelength of 1.3 μm. I
It is necessary to increase the composition of n, and in that case, there is a problem that the distortion amount becomes too large and the characteristics are deteriorated. In this sense, a crystal growth method for increasing the composition of nitrogen atoms in GaInNAs is required.

It is an object of the present invention to provide a compound semiconductor manufacturing method capable of easily manufacturing a group III-V compound semiconductor having a large composition of nitrogen atoms, and a semiconductor device manufactured by using the manufacturing method. is there.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the invention of claim 1 is as follows.
A group III-V compound semiconductor containing at least both arsenic atoms and nitrogen atoms as group V atoms is formed by a vapor phase growth method.
A method for producing a compound semiconductor using a nitrogen source gas, wherein a ratio of a partial pressure of an arsenic source gas to a sum of partial pressures of a group III source gas in a reaction vessel is 1 or less.

According to a second aspect of the present invention, there is provided the compound semiconductor according to the first aspect, wherein the group III-V compound semiconductor contains at least a gallium atom as a group III atom, and a composition of a nitrogen atom is smaller than a composition of an arsenic atom. It is a manufacturing method.

According to a third aspect of the present invention, the nitrogen source gas comprises:
Ammonia, hydrazine, monomethylhydrazine, 1,
3. The method for producing a compound semiconductor according to claim 1, wherein the compound semiconductor comprises at least one selected from 1-dimethylhydrazine, tertiary butyl hydrazine, and tertiary butylamine.

According to a fourth aspect of the present invention, there is provided a group III-V compound semiconductor containing both arsenic atoms and nitrogen atoms produced by using the compound semiconductor manufacturing method according to any one of the first to third aspects. Semiconductor device.

[0018]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a structure of a semiconductor device manufactured by using a compound semiconductor manufacturing method according to a preferred embodiment of the present invention.

As shown in FIG. 1, a semiconductor device 1 according to the present invention is mainly used for a light emitting device and a light receiving device. An undoped GaAs buffer layer 3 is provided on a Si-doped n-type GaAs substrate 2. Undoped GaI having a large composition of nitrogen atoms is formed on the GaAs buffer layer 3.
An nNAs layer 4 is formed, and an undoped GaAs cap layer 5 is formed on the GaInNAs layer 4.

In this semiconductor device 1, a GaAs substrate 2 is placed in a reaction vessel of a conventional MOVPE apparatus by, for example, a metalorganic vapor phase epitaxy (MOVPE) method as a vapor phase growth method, and a raw material gas is placed in the reaction vessel. And GaAs
It is manufactured by sequentially growing crystals on the s substrate 2.

In order to obtain a GaInNAs crystal having a large nitrogen atom composition, as described above, a crystal growth method for controlling the attachment / removal of arsenic reactive species and nitrogen reactive species on the crystal surface is required.

The method of manufacturing a compound semiconductor according to the present invention is directed to a method of manufacturing a compound semiconductor comprising a group III-V compound semiconductor containing at least both arsenic atoms and nitrogen atoms as group V atoms.
This is a method of manufacturing the NAs layer 4 by a MOVPE method using a nitrogen source gas.
When producing the aInNAs layer 4, the ratio of the partial pressure of the arsenic source gas to the sum of the partial pressures of the group III source gas in the reaction vessel (A
(s / III ratio) is set to 1 or less.

Here, the arsenic source gas and the nitrogen source gas used are not particularly limited. As the nitrogen source gas, for example, one or more types of materials selected from ammonia, hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, tertiary butyl hydrazine, and tertiary butylamine can be used.

If the As / III ratio is greater than 1, arsenic atoms and group III atoms are preferentially bonded, which hinders bonding between nitrogen atoms and group III atoms. Therefore,
Reduce the As / III ratio to 1 or less and do not bond with arsenic atoms III
The nitrogen atoms and III
The bond with the group atom is effectively promoted.

As described above, according to the method for manufacturing a compound semiconductor according to the present invention, the arsenic source gas is supplied into the reaction vessel at a low As /
Not supplied with arsenic atoms by supplying at III ratio III
Since the group atoms increase, the group III atoms that are not bonded to the arsenic atoms can be bonded with more nitrogen atoms that are less likely to adhere to the crystal surface than the arsenic atoms and are easily detached from the crystal surface.

Therefore, III having a large nitrogen atom composition
A -V group compound semiconductor can be easily manufactured, and a semiconductor device having an active layer or the like made of a III-V group compound semiconductor having a large nitrogen atom composition can be easily manufactured.

Since this semiconductor device includes a III-V compound semiconductor having a large composition of nitrogen atoms, the amount of distortion does not need to be so large, and higher performance can be obtained.
For example, when a light emitting element or a light receiving element is manufactured as a semiconductor element, not only optical communication in the 1.3 μm band but also 1.55
It can also be used for optical communication in the μm band.

Further, since the present invention provides a method for manufacturing a compound semiconductor in which the composition of nitrogen atoms can be easily increased, the composition of nitrogen atoms is usually increased as described later in Example 2. Among III-V compound semiconductors that contain at least gallium atoms as Group III atoms and at least both nitrogen atoms and arsenic atoms as Group V atoms, the composition of nitrogen atoms is smaller than that of arsenic, In the method for manufacturing a compound semiconductor, the ratio of the number of nitrogen atoms to the number of arsenic atoms contained in the compound semiconductor is more than 0 and less than 1, the effect of the present invention can be obtained.

[0030]

(Embodiment 1) An example of a method of manufacturing the semiconductor device 1 described with reference to FIG. 1 will be described in more detail.

As shown in FIG. 1, the semiconductor element 1 is made of Si
On the doped n-type GaAs substrate 2 by MOVPE method,
An undoped GaAs buffer layer 3 having a thickness of 500 nm;
An undoped GaInNAs layer 4 having a thickness of 500 nm and an undoped GaAs cap layer 5 having a thickness of 100 nm are grown in this order.

To manufacture layers other than the GaInNAs layer 4,
Trimethylgallium (TMGa) and 10% arsine (AsH ₃ ) diluted with hydrogen were used as raw materials, and were fed into the reaction vessel by hydrogen gas.

The growth temperature is 650 ° C., the pressure in the reaction vessel is 66.7 hPa (50 torr), the carrier gas is hydrogen, and the total flow rate of the gas supplied into the reaction vessel is 4 slm.
And At this time, the ratio of the sum of the partial pressures of the group V source gas to the sum of the partial pressures of the group III source gas (V / III ratio) is about 10, which is the same value as the As / III ratio.

For the production of the four layers of GaInNAs, triethyl gallium (TEGa), trimethyl indium (TMIn), ammonia (NH ₃ ) and hydrogen-diluted AsH ₃ were used as raw materials, and were fed into the reaction vessel with hydrogen gas. The actual supply flow rates of TEGa, TMIn, and AsH ₃ are each 0.37 sccm (1.7 × 10 ⁻⁵ mol / mi).
n), 0.015 sccm (6.7 × 10 ⁻⁷ mol / m)
in), 1000 sccm (4.5 × 10 ^-2 mol / m)
in) and 0.31 sccm (1.4 × 10 ⁻⁵ mol /
min).

The growth temperature is 550 ° C., the pressure in the reaction vessel is 66.7 hPa (50 torr), the carrier gas is hydrogen, and the total flow rate of the gas supplied into the reaction vessel is 4 slm.
And At this time, the V / III ratio was about 2600 and As / III
The ratio is less than or equal to 0.8.

When the sample after growth was analyzed by a secondary ion mass spectrometer (SIMS), the GaInNAs layer 4 was analyzed.
Had an N concentration of 4.2 × 10 ²⁰ cm ⁻³ . This corresponds to about 2% of the composition of nitrogen atoms. Further, from this result and the result of the X-ray diffraction measurement, the In composition was derived to be about 8%.

Further, at room temperature, photoluminescence (P
L) Upon measurement, a spectrum as shown in FIG. 2 was obtained. FIG. 2 shows a spectrum diagram of photoluminescence measurement of the semiconductor element 1 with the horizontal axis representing wavelength (μm) and the vertical axis representing PL intensity (arbitrary unit). This peak wavelength was 1.16 μm.

In the PL measurement, light such as a laser having a photon energy larger than the band gap energy of the sample is excited on the sample, and a two-dimensional image of light emission accompanying interband transition in the active layer is obtained. This is to judge whether the luminous efficiency is good or not.

As described above, by supplying the arsenic source gas into the reaction vessel so that the As / III ratio becomes smaller than 1, the GaInNAs layer 4 having a high nitrogen composition of about 2% can be easily obtained. Moreover, it was confirmed that the crystals were good.

(Embodiment 2) Next, Embodiment 2 will be described.
In the second embodiment, the GaInNAs layer 4 described in the first embodiment is used.
Is applied to an active layer of a semiconductor laser.

FIG. 3 is a sectional view showing the structure of a semiconductor laser as a semiconductor device according to the present invention.

As shown in FIG. 3, a semiconductor laser 31 according to the present invention comprises a Si-doped n-type GaAs buffer layer 33 having a thickness of 500 nm and a thickness of 1500 nm formed on a Si-doped n-type GaAs substrate 32 by MOVPE. Si
Doped n-type Al _0.75 Ga _0.25 As lower cladding layer 34,
50 nm thick undoped GaAs lower optical guide layer 35
d, a multiple quantum well active layer 36 having a thickness of 44 nm having three well layers, an undoped GaAs upper optical guide layer 35 u having a thickness of 50 nm, and Mg-doped p-type Al having a thickness of 1500 nm.
_An upper cladding layer 37 of _0.75 Ga _0.25 As and a Mg-doped p-type GaAs contact layer 38 having a thickness of 20 nm are grown in this order, and the upper cladding layer 37 is formed to have a convex cross section by etching and the contact layer 38 is formed to have a stripe shape. Then, AuGe is formed on the lower surface of the GaAs substrate 32.
A Ni lower electrode 39 is formed, and an AuZn upper electrode 40 is formed on the upper surface of a stripe-shaped contact layer 38. The semiconductor laser 31 is a so-called quantum well laser, and has a characteristic of a low oscillation threshold current.

Here, the multiple quantum well active layer 36 is formed as shown in FIG.
As shown in FIG. 2, each layer is undoped GaIn having a thickness of 8 nm.
The three layers of the NAs well layer 41 and the GaI
Each of the layers sandwiched between the nNAs well layers 41 has a five-layer structure including two layers of an undoped GaAs barrier layer 42 having a thickness of 10 nm.

For fabrication other than the multiple quantum well active layer 36,
TMGa was used as a Ga raw material, trimethylaluminum (TMAl) was used as an Al raw material, and 10% AsH ₃ diluted with hydrogen was used as an As raw material, and each raw material was fed into the reaction vessel with hydrogen. The carrier gas supplied into the reaction vessel was hydrogen gas, and the total flow rate of the gas supplied into the reaction vessel was 4 slm. The pressure in the reaction vessel was 66.7 hPa (50 torr), and the temperature was 650 hPa.
The crystals were grown while being kept at ℃.

To manufacture the multiple quantum well active layer 36, Ga
TEGa was used as the raw material, TMIn was used as the In raw material, 1,1-dimethylhydrazine (UDMHy) was used as the N raw material, and 10% AsH ₃ diluted with hydrogen was used as the As raw material. The actual supply flow rates were 0.37 sccm (1.7 × 10 ^−), respectively. ^Five
mol / min), 0.029 sccm (1.3 × 10
^-6 mol / min), 500 sccm (2.2 × 10 ^-2)
mol / min) and 0.32 sccm (1.4 × 10
^-5 mol / min). Hydrogen gas was used as the carrier gas, and the total flow rate of the gas supplied into the reaction vessel was 4 s.
lm, and the pressure in the reaction vessel was 66.7 hPa (50
torr) and the temperature was 550 ° C. At this time, V / II
The I ratio is 1250, and the As / III ratio is 0.8, which is 1 or less.

The epitaxial wafer thus grown was processed into a ridge-type Fabry-Perot laser having a stripe width of 2 μm and a resonator length of 300 μm to produce a semiconductor laser 31, and its laser characteristics were evaluated. Semiconductor laser 3 at room temperature
1 can be confirmed, and the oscillation wavelength is about 1.
It was 29 μm. FIG. 5 shows the oscillation spectrum at room temperature. FIG. 5 shows a room temperature oscillation spectrum diagram of the semiconductor laser 31 with the horizontal axis representing wavelength (μm) and the vertical axis representing emission intensity (arbitrary unit).

On the other hand, aside from the semiconductor laser 31, a GaInNAs layer having a thickness of 300 nm is grown on a Si-doped n-type GaAs substrate under the same growth conditions as the GaInNAs well layer 41 used here. According to SIMS analysis, the N concentration was 8.3 × 10 ²⁰ atoms / c.
m ³ . This corresponds to a composition of nitrogen atoms of about 4%. In addition to the X-ray diffraction measurement, the In composition was determined to be 15%, and the composition of the GaInNAs well layer 41 was found to be Ga _0.85 In _0.15 N _0.04 As _0.96 .

Thus, the GaInNAs well layer 41 is formed.
Was produced by a simple method according to the present invention, and it was confirmed that the composition of nitrogen atoms was large and that it was a good crystal. In addition, since the semiconductor laser 31 includes the GaInNAs well layer 41 having a large composition of nitrogen atoms, it was confirmed that the distortion amount was small, and the device characteristics were better and the performance was higher than before. Further, a semiconductor laser having an oscillation wavelength of 1.55 μm can be manufactured in the same manner as in Example 2 described above.

In the above embodiment, the GaInNAs layer 4 and the G
a, Ga, In, A for forming the aInNAs well layer 41
As raw materials for s and N, TEGa, TMIn,
The example using AsH ₃ and NH ₃ or UDMHy has been described. However, the raw material is not limited to these, and any raw material may be used as long as the condition that the As / III ratio is 1 or less is satisfied. For example, tertiary butyl arsine (TBAs) can be used as an As material, and TMGa or TM
In can also be used.

In the second embodiment, the GaInNAs crystal manufactured by the method of manufacturing a compound semiconductor according to the present invention is applied to an edge-emitting Fabry-Perot type semiconductor laser. It is not limited to type semiconductor lasers, but is applied to edge emitting distributed feedback semiconductor lasers, surface emitting semiconductor lasers, light emitting elements such as light emitting diodes, light receiving elements such as photodiodes, other solar cells and electronic devices, etc. However, the effect of higher performance than before can be obtained without excessively increasing the amount of distortion.

[0051]

As is apparent from the above description,
According to the present invention, the following excellent effects are exhibited.

(1) By setting the ratio of the partial pressure of the arsenic source gas to the sum of the partial pressures of the group III source gas to 1 or less,
A group III-V compound semiconductor having a large composition of nitrogen atoms can be easily obtained. Thereby, a crystal having a band gap wavelength of 1.3 μm can be obtained without increasing the amount of strain so much.

(2) A crystal having a bandgap wavelength of 1.55 μm can be easily produced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a semiconductor device according to the present invention.

FIG. 2 is a spectrum diagram of the semiconductor device shown in FIG. 1 obtained by photoluminescence measurement.

FIG. 3 is a sectional view showing a structure of a semiconductor laser according to the present invention.

FIG. 4 is a sectional view showing a structure of an active layer of the semiconductor laser shown in FIG. 3;

5 is a diagram showing a room-temperature oscillation spectrum of the semiconductor laser shown in FIG. 3;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 semiconductor element 2 Si-doped n-type GaAs substrate 3 undoped GaAs buffer layer 4 undoped GaInNAs layer (III-V compound semiconductor layer containing both arsenic atoms and nitrogen atoms) 5 undoped GaAs cap layer

Continuation of front page    (72) Inventor Katsuya Akimoto             1-6-1 Otemachi, Chiyoda-ku, Tokyo Sun             Standing wire company F term (reference) 4K030 AA09 BA08 BA11 BA25 BA38                       CA04 CA12 FA10 JA09 LA14                 5F041 AA11 AA40 CA34 CA35 CA65                       FF14                 5F045 AA04 AB18 AC01 AC08 AC09                       AC12 AD10 AE23 BB12 CA12                       DA53 DA63                 5F073 AA13 AA45 AA74 BA02 CA05                       CA17 CB02 DA05 EA02 EA29

Claims (4)

[Claims] 1. A method for producing a group III-V compound semiconductor containing at least both an arsenic atom and a nitrogen atom as a group V atom by a vapor phase growth method using a nitrogen source gas, the method comprising: A method for producing a compound semiconductor, wherein a ratio of a partial pressure of an arsenic source gas to a sum of partial pressures of a group III source gas is set to 1 or less. 2. The method according to claim 1, wherein the III-V compound semiconductor contains at least gallium atoms as group III atoms, and the composition of nitrogen atoms is smaller than that of arsenic atoms. 3. The method according to claim 1, wherein the nitrogen source gas contains at least one selected from ammonia, hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, tertiary butyl hydrazine, and tertiary butyl amine. A method for manufacturing a compound semiconductor. 4. A compound semiconductor comprising a group III-V compound semiconductor containing both arsenic atoms and nitrogen atoms, which is manufactured by using the method for manufacturing a compound semiconductor according to claim 1. Semiconductor device.